The supplements which may have this effect include aloe, chromium, ginseng, and CoQ10, and there is weaker evidence for about 30 others. See the list of these supplements and get more information in the Insulin article, which is part of the extensive Drug Interactions section of our website (where you can also look up supplement interactions for other drugs you may be taking).

ConsumerLab.com Answers

Question:Which supplements can help lower or control my blood sugar?

Answer:Many different supplements may help lower or control blood sugar in people with prediabetes or type 2 diabetes who experience hyperglycemia (when blood glucose rises higher than normal). These supplements are discussed below. More details about each, including dosage, drug interactions, potential side effects, and ConsumerLab.com's reviews of products on the market, can be found by clicking on the links.

Due to the seriousness of hyperglycemia, it is important to consult with your physician regarding use of these supplements.

Cinnamon supplements may modestly improve blood sugar in people with type 2 diabetes whose blood sugar is not well controlled with medication. In addition, one small study found that a branded cinnamon extract reduced fasting blood sugar by an average of about 10 mg/dL in prediabetic men and women with metabolic syndrome. Keep in mind, however, that only certain varieties of cinnamon have been shown to have this effect, and long-term safety studies have not been conducted.

Curcumin (from turmeric) may improve blood sugar levels, according to preliminary studies, and one study found curcumin to dramatically lower the chances of prediabetes in middle-aged, slightly overweight men and women with somewhat higher than normal blood sugar levels.

Alpha lipoic acid may improve insulin sensitivity and blood sugar control in people with type 2 diabetes, although it may only slightly reduce levels of glycosylated hemoglobin (HbA1c).

Chromium picolinate may help some people with type 2 diabetes decrease fasting blood glucose levels as well as levels of insulin and glycosylated hemoglobin (HbA1c). However, be aware that high doses may worsen insulin sensitivity in healthy people who are not obese or diabetic.

Having adequate blood levels of vitamin D may reduce the risk of insulin resistance in people who are obese. There is some evidence that a certain blood level of vitamin D is needed for normal glucose metabolism in women who are overweight and obese (but not diabetic), but it is not clear whether any further benefit is gained with higher blood levels.

In healthy people, consuming a moderate amount of olive oil with a meal has been shown to reduce increases in blood sugar after the meal compared to the same meal consumed with corn oil. In people with type 1 or type 2 diabetes, olive oil may improve glucose metabolism.

Increasing dietary fiber, especially insoluble fiber from cereal and grains, is associated with a reduced risk of diabetes and has been shown to reduce fasting blood glucose and modestly lower HbA1c in people with type 2 diabetes (Martin, J Nutr 2008; Post,J Am Board Fam Med 2012). In people with type 1 diabetes, 50 grams of dietary fiber per day has been shown to significantly improve blood sugar control and reduce hypoglycemic events (Giacco, Diabetes Care 2000). The American Dietetic Association states that "diets providing 30 to 50 g fiber per day from whole food sources consistently produce lower serum glucose levels compared to a low-fiber diet. Fiber supplements providing doses of 10 to 29 g/day may have some benefit in terms of glycemic control." (Slavin, J Am Diet Assoc 2008). Although ConsumerLab.com has not tested fiber products, we have produced a webinar about that provides more information.

Ginseng, both American and Korean Red ginseng (from Panax ginseng), may reduce blood sugar levels in people with diabetes, according to preliminary research.

Drinking whey protein before a high glycemic meal may help to lessen increases in blood sugar after the meal in people with well-controlled type 2 diabetes.

Silymarin, a component of milk thistle, may decrease blood sugar and hemoglobin A1c in people with type 2 diabetes, and reduce insulin resistance in people with coexisting diabetes and alcoholic cirrhosis.

Inulin, a type of prebiotic, may improve measures of blood sugar control in women with type 2 diabetes, although it did not improve blood sugar levels or insulin resistance in a study of prediabetic men and women.

Berberine (a compound found in plants such as barberry, Oregon grape and goldenseal) may reduce blood sugar levels in people with metabolic syndrome or type 2 diabetes, according to a few small studies.

Fenugreek may help to lower blood sugar, according to preliminary studies, and one study found fenugreek extract to significantly improve some measures of blood sugar control and insulin response in people with type 2 diabetes.

White mulberry (Moruns alba or Morus indica) has been traditionally used in Asia to help treat type 2 diabetes, and there is some preliminary evidence to support this use. Mulberry leaf extract (species not given) may lessen increases in blood sugar after ingestion of table sugar in healthy people and people with type 2 diabetes (Mudra, Diabetes Care 2007). Among people with type 2 diabetes, taking 1 gram of powdered white mulberry leaf three times daily (after breakfast, lunch and dinner) for four weeks was found to lower fasting blood sugar by 27%, while taking 5 mg of the anti-diabetes drug glibenclamide lowered fasting blood sugar by only 8% (Andallu, Clin Chim Acta 2001).

There is mixed evidence as to whether CoQ10 may lower blood sugar. To be safe, people with diabetes or who take medication to lower blood sugar should consult a physician before using.

There are a few supplements which may worsen blood sugar control or insulin sensitivity in certain people: excessive amounts of niacin may elevate blood sugar levels, and prescription digestive enzymesmay cause an increase or decrease in blood sugar levels in people with exocrine pancreatic insufficiency. CLA (conjugated linoleic acid), a popular supplement for slimming, may worsen blood sugar control in diabetics and in obese people without diabetes.

Although fish oil does not appear to adversely affect blood sugar levels in people with diabetes, one study reported that a large daily dose of krill oil (providing a modest amount of EPA and DHA) reduced insulin sensitivity in overweight, middle-aged men by about 27% -- which could potentially increase the risk of diabetes.

Also note that high doses of vitamin C may increase blood sugar or interfere with certain blood sugar tests.

ConsumerLab.com Answers

Question:Are the "% DV" numbers on vitamin supplement labels really based on what I need?

Answer:Yes and no. The most current DVs (Daily Values), updated by the FDA in 2016, do accurately reflect the basic daily intake requirements for vitamins and minerals. However, companies are not required to use the updated DVs on product labels until at least 2020. In the meantime, many vitamin and supplement labels will be misleading — providing "%DV" values based on terribly out-dated DVs establish in the 1960s. The new DVs include separate values for infants, very young children, and women who are pregnant and lactating.

Some important changes in 2016 to the DVs for most adults and children over age 4 include the following. (Keep in mind that your supplement label is most likely still based on old DVs):

Vitamin D: The DV doubled, from 400 IU (10 mcg) to 800 IU (20 mcg). (Note: Many people who are not deficient in vitamin D may already be taking too much.) Labels will also have to list vitamin D in different units (mcg), but can include the familiar IU (international units) values (1 mcg = 40 IU).

Folate: Recognizing that about 70% more folate is absorbed from supplements containing folic acid (synthetic folate) than from foods naturally containing folate, the DV (which remains at 400 mcg) is now based on "dietary folate equivalents," shown as "DFE". A supplement with 400 mcg of folic acid is to be labeled as providing 170% DV rather than 100% DV.

ConsumerLab.com lists the new DVs (as well as RDAs and Upper Tolerable Intake Levels (ULs)) for each vitamin and mineral at www.consumerlab.com/rdas.

You'll find further information about each nutrient within our Product Reviews, including our tests, reviews, ratings, and comparisons of products.

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Product Reviews

Chromium Supplements Review

Initial Posting: 7/7/18

Chromium Supplements Review

Best Chromium Supplements Identified -- By Strength

Alphabetical list of chromium-containing supplement brands we compared in this report

365 [Whole Foods] Chromium Picolinate

Ortho Molecular Products Reacted Chromium

Source Naturals Chromium Picolinate

ez Melts Chromium

Puritan's Pride Chromium Picolinate

Spring Valley [Walmart] Chromium Picolinate

GNC Chromium Picolinate

Make sure the chromium supplement you take passed our test and is right for you!
Isn't your health worth it?

Chromium is an essential mineral, important for insulin function. Chromium supplementation is promoted to help with blood sugar control in people with type 2 diabetes and with weight loss. But does it really work, and if so, which products are best?

ConsumerLab.com recently tested popular chromium supplements and reviewed the clinical evidence. After purchasing chromium products at retail, each was tested for its amount of chromium and potential contamination with a potentially toxic form of chromium known as hexavalent chromium or chromium VI. All tablets and caplets were tested to be sure they would break down properly in disintegration tests.

Among the products that passed our tests, we selected our Top Picks, representing the best quality and value. These Top Picks include those providing 200 mcg, 500 mcg, and 1,000 mcg per unit, because there is a wide variation in strength among products. This means that if you rely on supplement labels, you could be getting too much chromium, or not enough, depending on your needs and your reason for taking it.

You must be a ConsumerLab.com member to get the full test results and reviews for seven chromium supplements. Six of these were selected for review by ConsumerLab.com and one other product passed the same testing in CL's voluntary Quality Certification Program. In the report, you'll learn:

ConsumerLab's Top Picks for chromium supplements based on quality, dose and value

Which products passed or failed our tests and why

How chromium supplements compare on ingredients, dosage, and cost

The pros and cons of different forms of chromium (such as chromium picolinate, chromium polynicotinate, chromium chloride) and which may be best for you — plus, what you should know about "GTF" chromium

Dosage of chromium for specific uses and the evidence for or against those uses (including diabetes, weight loss, hypoglycemia, and memory enhancement)

Safety, side effects, and other concerns to consider when using chromium supplements